Morphology and Virulence of Trypanosoma cruzi-like Hemoflagellates Isolated from Wild Mammals in Georgia and Florida

Abstract

During epizootiological investigations of leptospirosis in wild animals in southwestern Georgia and northwestern Florida, hemoflagellates resembling Trypanosoma cruzi were recovered from 103 of 1584 animals collected (Brooke et al, 1957; McKeever et al, 1958). The organisms were found in cultures of kidney tissue from 17 percent of 552 opossums, 1.7 percent of 118 grey foxes, 1.5 percent of 608 raccoons and 1.1 percent of 306 striped skunks. Triatomid bugs were found only rarely in the areas where the animals were collected, and no human cases of Chagas' disease have been reported to date. T. cruzi and T. cruzi-like organisms have, however, been isolated from several species of Triatoma in the United States (Wood and Wood, 1941; Sullivan et al, 1949; and Usinger, 1944). Species of wood rat, wood mouse, deer mouse, opossum, bat, armadillo (Usinger, 1944; Wood, 1952) and raccoon (Walton et al, 1958) have been reported as reservoir hosts. Identifications of the organisms were usually based on the morphology and cyclical development in insect and mammalian hosts. Studies of virulence and infectivity rates of these organisms have been hampered by the great variations in susceptibility of laboratory animals toward infection with T. cruzi (Mazzotti, 1940; Hauschka, 1949; Pizzi et al, 1949). Although there is some experimental evidence that wild animal hemoflagellate isolates can infect domestic animals, man and other primates (Diamond and Rubin, 1958; Packchanian, 1943; Davis, 1943), it is still not known whether any or all are capable of producing Chagas' disease. Nor is it known whether the virulence of animal strains can be increased by passage through new hosts under natural conditions. Serological tests for the identification of species and/or strains of hemoflagellates have had limited use (Hauschka, et al, 1950; Packchanian and Turck, 1949; Senekjie, 1943; Walton, et al, 1958). The present report concerns the comparative study of 7 strains of hemoflagellates isolated during a leptospirosis field study. In order to identify the wild animal isolates, their characteristics were compared with those of 3 established species of Trypanosoma; namely, T. cruzi, T. rangeli, and T. duttoni.